Hydraulic jack having lifting beam forces applied by rollers to provide for horizontal movement



Jan. 2, 1968 I M. R. STAHL 3,361,409

HYDRAULIC JACK HAVING LIFTING BEAM FORCES APPLIED BY ROLLERS TO PROVIDE FOR HORIZONTAL MOVEMENT Filed Dec. 12, 1966 5 :l i I i 42 414 g 0' I a 44 l6 0 I Ill/Ill/ III! II/ II I I I I FIG, 2

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A T TOR/VEYS United States Patent 3,361,499 HYDRAULIC JACK HAVING LIFTING BEAM FGRCES AIWLIED BY ROLLERS TO PRO- VIDE FOR HORIZONTAL IVIOVEMENT Myron R. Stahl, 612 N. Sierra Drive, Beverly Hills, Calif. 90210 Filed Dec. 12, 1966, Ser. No. 605,124 Claims. (Cl. 254-8) This invention relates to hydraulic jacks.

Hydraulic jacks for raising heavy objects such as airplanes frequently utilize classical leverage relationships, because in many instances there is insuflicient clearance in which to fit direct-lifting cylinder-type jacks. For example, the confined space between the wheels of an airplane is often too small to provide access for bulky power devices such as cylinders. The lever arrangement permits such bulky power devices to be used, but still to be spaced away from the object to be lifted, and permits the lifting point to be disposed at the end of a relatively slim tongue which can be placed into narrow quarters, such as between the wheels of an airplane.

When a lever-type jack is used, it is common for forces to be exerted at each end of the lifting beam in a downwardly direction while another force in an upwardly direction reacts on the lifting beam in a more central position. The object is raised by lifting the central pivot point of the jack or by lowering the end which is extreme from the load. In conventional devices there is a tendency for that end of the lifting beam which supports the object to follow an arcuate path unless means are taken to avoid this. Such an arcuate path is undesirable because either the jack or the object to be lifted must shift in the direction of the horizontal vector of the arcuate path in order for the lifting of the object to proceed. Elimination of the arcuate path is desirable to eliminate this horizontal shift and thereby relieve side-load stresses in the plane of the horizontal movement within the object to be lifted and within the jack which, in time, could seriously weaken said object and said jack, and which cause undesirable imbalanced loads during lifting operations.

An object of the present invention is to provide a levertype jack which will eliminate any tendency of the load to follow an arcuate path and thereby relieve side-load stresses in the plane of the horizontal movement within both the jack and the object to be lifted.

The jack of the present invention generally comprises a base, a hydraulic lifting means supported by said base and a lifting beam means having a tongue extending therefrom. A first supporting means is fixed to said hydraulic lifting means for supporting said beam means at a first point while a second supporting means is fixed to said base for supporting said beam means at a second point. Said first supporting means comprises a first roller means abutting a first reactive surface and said second supporting means comprises a second roller means abutting a second reactive surface whereby said lifting beam means is capable of moving in a substantially horizontal direction by action of said rollers on said reactive surfaces.

Another object of the present invention is to provide a lever-type jack whereby an object may be vertically lifted without an arcuate movement.

An optional and preferred object of this invention is to provide a spring means for a lever-type jack whereby the horizontal movements of the lifting beam are restricted from traveling beyond predetermined limits.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 shows a top view of the jack of the present invention;

3,361,409 Patented Jan. 2, 1968 ice FIG. 2 shows a side view of the jack of FIG. 1 taken along line 22 of FIG. 1;

FIG. 3 shows another side view similar to FIG. 2 only with the jack in an elevated position; and

FIG. 4 shows a front view of the jack of FIG. 1.

The jack generally comprises a base 10 having a pair of cylindrical extensions 12 and 12a connecting to a pair of wheel assemblies 14 and 14a respectively. The base of the jack also connects to a third wheel assembly 16 and a suitable tow handle connection 18. Wheels 20 and 20a, contained in wheel assemblies 14 and 14a, are preferably spring loaded, as is wheel assembly 16. The cylindrical extensions 12 and 12a preferably contain a reservoir of hydraulic fluid for the hydraulic pump, schematically shown at 17, for lifting a hydraulic cylinder 30. Alternatively, the reservoir of hydraulic fluid may be separate from extensions 12 and 12a or even remote from the jack. Bypass valve 19 may be used for lowering the cylinder and returning fluid to the reservoirs in 12 and 12a. Cap 11 closes a filler port to the reservoir in 12 and 12a through which port hydraulic fluid may be added. Conduit 13 connects the valve and pump with the reservoir while conduit 15 connects the valve and pump with the hydraulic cylinder.

A pair of arms 24 and 24a are connected to the cylindrical extensions 12 and 12a respectively, preferably at the furthermost end from the center of the jack. A pair of pads 22 and 22a are connected to the front ends of arms 24 and 24a, respectively, and are preferably positioned to rest firmly on the ground ahead of the tongue 43 of the lifting beam. Alternatively, pads 22 and 22a may be positioned to rest on the ground behind the end of the tongue allowing the tongue to protrude beyond the pads. Likewise, arms 24 and 24a may be connected to the extensions 12 and 12:: at a medial point. The positions of the arms and pads are given by way of example and not of limitation and are primarily determined by the space limitation of the object to be lifted. The base 10 further may include a suitable support structure 26 for structural support of the cylinder 36 located between the cylindrical extensions 12 and 12a.

Located medially of the structural support is a piston 28 supported by base 10 and support 26. A cylinder 30 rides on the piston and is adapted to move in an upward and downward direction, as indicated in FIGS. 2 and 3. A pair of rollers 32 and 32a are supported by a yoke 34 which is connected to the cylinder 39 in such a manner that the rollers move in an upward and downward direction with the cylinder.

At the rear of the jack a roller 36 is shown supported by a pair of vertical supports 38 and 38a which are, in turn, connected to the base 10. The wheel assembly 16 and tow handle connection 18 are connected to the base 10 and the vertical supports 38 and 38a with a suitable coupling mechanism 40.

The lifting beam 42 has a substantially arcuate reactive surface 46 and a substantially flat reactive surface 48. The arcuate reactive surface of the lifting beam 42 rests upon rollers 32 and 3211 while the flat reactive surface of the lifting beam is supported from its top by roller 36. A lifting cup 44 is located at one end of a tongue 43 extending from said lifting beam; said beam being positioned so that the arcuate reactive surface 46 is supported by roller 32 while the other end of the beam is restrained from vertical movement by action of roller 36 on reactive surface 48.

In operation the lifting cup 44 is placed under a heavy object such as an airplane and the cylinder 30 is raised by the hydraulic system and pump. The pump 17 may be a manual pump, an electrical pump, or a pneumatic pump as desired. As cylinder 36 rises, it lifts rollers 32 and 32a, which in turn bear against the reactive surface 46, and lift 3 the beam at its medial point, causing the lifting beam 42 to rise.

If, instead of being placed on rollers, the lifting beam 42 were fixed at either of points 32 or 36, the lifting cup 44 would follow a substantially arcuate path, as exhibited by any fixed, second-class lever. However, the lifting beam 42 is placed on rollers 32, 32a and 36 in such a manner as to eliminate any arcuate path that cup 44 may tend to take. When weight is first placed on cup 44, the wheels 20 and 20a, being spring loaded, allow pads 22 and 22a to lower and bear upon the ground. The lifting beam 42 initially moves toward the rear of the jack on rollers 32, 32a, and 36 until the arcuate path, if it existed, would be in its extreme horizontal position. At this point the lifting beam 42 begins to move forward upon the rollers to allow the cup 44 to continue to rise in a substantially vertical direction.

The reactive surface 46 is designed to reduce any unnecessary or transient lateral movements of the jack. The radius of arcuate reactive surface 46 approximates the radius of the imaginary are that a beam of fixed pivot points would follow, e.g., a fixed lever. A leaf spring 50 is connected to the base 10 and passes through a space 52 within the lifting beam 42. A pair of pins or stop means 54 are positioned through the space 52 on either side of the leaf spring 50. The leaf spring 50 serves to prevent lateral movement in the horizontal direction past a predetermined limit. A pair of optional coil springs 56 are connected to the lifting beam 42 and to the vertical supports 38 and 38a. These springs serve to bias the lifting beam to its original, or rest, position when not in use.

It is to be understood that although the embodiment shown utilizes fixed roller points operating on reactive surfaces on the lifting beam itself, either or both points may utilize a roller fixed to the lifting beam for reaction on a reactive surface fixed to the base or the hydraulic lifting means. Likewise, although the cylinder is shown as movable over a fixed piston, the piston may be movable over a fixed cylinder. Further, it may be desirable in certain applications to move the farthest point from the load downwardly and maintain the central point stationary by utilizing a hydraulic cylinder arrangement at the rear of the. jack for this purpose.

This invention provides a lever-type jack capable of being placed into confined spaces for lifting heavy objects, such as airplanes, without an arcuate movement. The jack is rugged and provides a safe, sure lifting operation.

The term supporting means has been used herein in the sense of restraint of motion in some direction. While in some instances this also comprises means for holding a component off the ground the term supporting is not used in this limited a scope, but may, and as to roller 36 does, mean restricting the beam from upward movement.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.

I claim:

1. A jack for lifting an object, said jack having a base, a hydraulic lifting means supported by said base, a lifting beam means having a tongue extending therefrom, said tongue having a lifting point, first means fixed to said hydraulic lifting means for lifting said beam means at a first point, a second means fixed to said base for supporting said beam means at a second point, both of said means being spaced from said lifting point, said first means comprising a first roller means abutting a first reactive surface and said second means comprising a second roller means abutting a second reactive surface whereby said lifting beam means is capable of moving in a substantially horizontal direction by action of said rollers on said reactive surfaces to substantially relieve stresses within said jack and said object in the plane of the horizontal movement.

2. A jack according to claim 1 wherein said first reactive surface is arcuate at the contact with said first roller means.

3. A jack according to claim 1 wherein said hydraulic lifting means comprises a piston fixed to said base a hydraulic cylinder adapted to move on said piston, means mounting said first roller means on said cylinder and said first reactive surface being carried by said lifting beam means.

4. A jack according to claim 1 wherein means is provided to prevent lateral movement of said lifting beam means beyond a predetermined limit.

5. A jack according to claim 4 wherein said means to prevent lateral movement beyond a predetermined limit comprises a leaf spring fixed to said base, a pair of stop means fixed to said lifting beam means, said leaf spring being positioned between each of said stop means whereby when said lifting beam means is moved in one direction to a position such that said leaf spring contacts one of said stop means, said leaf spring biases said lifting beam means in the opposite direction.

6. A jack according to claim 5 wherein said hydraulic lifting means comprises a piston fixed to said base, a hydraulic cylinder adapted to move on said piston, means mounting said first roller means on said cylinder, and said first reactive surface being carried by said lifting beam means.

7. A jack according to claim 6 wherein said first reactive surface is arcuate at the contact with said first roller means.

8. In a lever-type jack having a lifting beam, said beam having two ends with a lifting point for contact with an object to be lifted adjacent to one of said ends; first means movable in a vertical direction for lifting one end of said beam in said vertical direction; second means for restrain ing the vertical movement of the other end of said beam; said first means comprising a first roller means abutting a first reactive surface; said second means comprising a second roller means abutting a second reactive surface whereby said beam is permitted to move in a horizontal direction to substantially relieve stresses within said jack and said object in the plane of the horizontal movement.

9. A jack according to claim 8 in which a hydraulic lifting means is fixed to a base, said first and second reactive surfaces being carried by said lifting beam, means mounting said first roller means to said hydraulic lifting means, and means mounting said second roller means to said base.

10. A jack according to claim 8 including a pair of stop means fixed to said beam, a base, and a spring adapted to be positioned between each of said stop means fixed to said base to prevent lateral movement of said beam beyond a predetermined limit. 

1. A JACK FOR LIFTING AN OBJECT, AND SAID JACK HAVING A BASE, A HYDRAULIC LIFTING MEANS SUPPORTED BY SAID BASE, A LIFTING BEAM MEANS HAVING A TONGUE EXTENDING THEREFROM, SAID TONGUE HAVING A LIFTING POINT, FIRST MEANS FIXED TO SAID HYDRAULIC LIFTING MEANS FOR LIFTING SAID BEAM MEANS AT A FIRST POINT, A SECOND MEANS FIXED TO SAID BASE FOR SUPPORTING SAID BEAM MEANS AT A SECOND POINT, BOTH OF SAID MEANS BEING SPACED FROM SAID LIFTING POINT, SAID FIRST MEANS COMPRISING A FIRST ROLLER MEANS ABUTTING A FIRST REACTIVE SURFACE AND SAID SECOND MEANS COMPRISING A SECOND ROLLER MEANS ABUTTING A SECOND REACTIVE SURFACE WHEREBY SAID LIFTING BEAM MEANS IS CAPABLE OF MOVING IN A SUBTANTIALLY HORIZONTAL DIRECTION BY ACTION OF SAID ROLLERS ON SAID REACTIVE SURFACES TO SUBSTANTIALLY RELIEVE STRESSES WITHIN SAID JACK AND SAID OBJECT IN THE PLANT OF THE HORIZONTAL MOVEMENT. 